Method of applying metal coatings to bodies and material for use therein



April 1D0, 1934. J A, DALY 1,954,403

METHOD OF APPLYING METAL COATINGS TO BODIES AND MATERIAL FOR USE THEREIN Filed May 25, 1930 ayt/vento /3 y fa/mnh@ Patented Apr. l0, 1934 METHOD F APPLYING METAL COATINGS TO BODIES AND MATERIAL FOB USE THEREIN,

John A. Daly, New nocheue, N. Y.

Application May 26, 1930, Serial No. 455,708

Claims.

This invention relates to coating with metal and has as an object the provision of a process of applying a coating of metal in the form of metal foil to objects comprising material such as 5 artificial resins, mixtures of artificial and natural resins, vulcanite, pyroxylin or the like.

It is a further object of the invention to provide a metal foil prepared ready for use in the process of the invention.

In the accompanying drawing:

Fig. 1 is a vertical section greatly magnified of a piece of foil, as tin, prepared for use in the process of the invention;

Fig. 2 is a like section of prepared gold foil;

Fig. 3 is a plan view of a piece of foil much magnified showing material prepared by a modified form of the invention;

Fig. 4 is a sectional view showing the step of applying prepared foil to a softened body of vulcanite or the like;

Fig. 5 is a sectional view showing the step of applying prepared foil to a lacquered body;

Fig. 6 is a sectional view showing a stencil for applying spots of oil or the like to the foil before etching; and

Fig. '7 is a diagrammatic view showing the step of electrodepositing metal upon the etched foil.

In carrying out the process of the invention a metal foil initially smooth upon its surfaces is etchedupon one surface with a usual etching acid to provide a surface having minute cavities therein and between the cavities minute projections integral with the material. In the case of pure metal foils such as tin or gold, the resulting crystal-like projections with their-interspersed cavities will be extremely minute and evenly spaced throughout the surface.

In etching the foil during its preparation ac- 40 cording to theinvention it is necessary to carry the treatment to a point where from one-fifth to one-third of the foil has been dissolved. Examination of the thus prepared foil shows that the resulting surface, if tin foil is used, has characteristics such as roughly indicated in Fig. 1. The crystalsof the material appear to resist the acid which eats away the material surrounding the the microscope a prepared gold foil has an aroffer, thev superior results are due to this undercutting of the cavities. This is borne out by the established fact that materially less etching than that indicated will not yield successful results.

The projections may be made larger and more irregular by the application of a foreign material as oily matter to the surface of the foil. This may be accomplished desirably by use of a stencil 13 having many perforations as pin pricks 14. If such a stencil be laid over the foil and the hand of the operator be rubbed over the stencil it will be found that when etched the foil will be well prepared for application.

The result of such an application of foreign material is roughly indicated in plan view much magnified in Fig. 3 of the drawing in which the areas 13 are protected from action of the etching treatment and the margins of such areas will be irregularly undercut so as tov in effect produce protuberances of enlarged size.

In any case it is found advantageous to remove the partially etched foil from the acid and to flush ofi' the surface with lclear water preferably by flowing a stream of water over the surface and to then return the foil to the etching bath. This is believed to remove the partially spent acid from the forming cavities thus allowing fresh acid to secure access to the bottoms of the cavities and giving better under cuts.

As a further modification the foil may be first etched either with or without the application of foreign material as described, and the resulting projections or crystals may be built up by electrodeposition of a metal upon the etched surface as illustrated in Fig. '1. By such treatment 95 it is found that the projections, protuberances or crystals which are integral at their bases with the body of the foil will be built higher while the bottoms of' the cavities or pits produced by the etching will receive little or none of the electrodeposition.

In the case of an impure foil as an alloy certain of the constituents of the alloy will be eaten away more rapidly than others thereof thus resulting in larger protuberances than would re- 105. suit in the etching of a pure metal foil. Since mostfoils prccurable are not chemically pure metal, the etching of such alloys will produce a very fine material for use in the process.

To apply the thus prepared foil to the body, 1N

the surface of the body is softened as by heat or by the application of an appropriate softening agent. If necessary the softening agent is then washed off from the surface of the body and the surface is dried and while still in the softened condition the foil 15 is placed with the etched surface 16 in contact with the surface to be coated and the foil is then pressed thereon and may be burnished to cause close contact, when the protuberances produced by the etching will be pressed into the softened surface and will become attached thereto so firmly as to be not capable of removal therefrom.

When applying the coating according to the process of the invention, and while the object to be coated is already in a softened condition it is only necessary to apply the etched foil to the object and give the object its final pressure, usually with a hot die, when the coating will be caused to yeffectively adhere.

For application of a coating,A according to the process, to an already finished object a desirable result may be obtained by applying a lacquer 17 made by dissolving a material of the same nature as that of the object in an appropriate solvent, either to the object or to the etched sur-v face of the foil or to both, the foil 15 being applied before the lacquer hardens on one of the surfaces or on either of them. The application of such a lacquer to bodies of material of the nature under consideration will in itself result in a softening of the existing surface of the body since the lacquer contains, as an ingredient, a solvent or softening agent for the material of the object.

Since the roughened surface is produced by taking away some of the material from the foil, the protuberances thus produced are integral with the body of the foil and when pressed into the body to be coated form an exceedingly strong bond between the coating and the body to which it is applied, the material of the integral body projecting into the undercut cavities of the foil and the foil and body becoming a unit for all practical purposes.

The foil may be cut into ornamental patterns or to the form of letters or monograms before application and thus produce many beautiful effects of ornamentation.

Minor changes may be made in the physical embodiment of the invention or in the steps of the process within the scope of the appended claimswithout departing from the spirit of the invention.

I claim:

1. The process of coating a body with metal foil which comprises applying a minute quantity of foreign material to the surface of the foil, etching the thus prepared foil surface, softening the surface of the body and pressing said etched surface into the softened surface of the body.

2. The process of coating a body with metal foil which comprises etching a surface of the foil, applying a lacquer comprising as an ingredient a material of the same nature as that of the body to one of the surfaces to be brought into contact and immediately pressing the etched surface of the foil upon the body with the lacquer between the surfaces before the lacquer dries.

3. The process of coating a body with metal foil which comprises etching a surface of the foil, applying a coating of lacquer to the body and to the etched surface of the foil, said lacquer having as an ingredient a material of the same nature as that of the material of the body, and pressing the etched and lacquered surface of the foil against the lacquered surface of the body.

4. The process of coating a body with metal foil which comprises, applying oily matter to a plurality of separated spots upon a surface of the foil, etching the thus prepared surface, pressing the etched surface upon a softened surface of the body.

5. The process of coating a body of thermoplastic material with metal foil which comprises etching a surface of the foil to a depth to pron vide undercut protub'erances integral with the body of the foil and messing the etched surface of the foil against a surface of the body while in a plastic state to cause the material of the body to enter the spaces between said protuberances and to interlock with said undercuts.

JOHN A. DALY. 

